CODEWITHSUNDEEP
ruby-on-railsruby-on-rails-3rails-migrations
kalelc
kalelc

Reputation: 1527

Rails 3, generate migration with foreign key

How I can do or generate a migration with a foreign key? I have municipios table, and I want to relate with the table ciudades, the table will have these fields: nombre_id (name id), nombre (name), departamento (department) in this case how I can run the scaffold script to generate the foreign key migration?

Upvotes: 4

Views: 5178

Answers (2)

ahmy
ahmy

Reputation: 4365

If you mean that you want to create the migration file the command is

rails generate migration NAME [field:type field:type] [options]

or shortcut

rails g migration NAME [field:type field:type] [options]

But if you want to create a scaffold from model that referencing other model. Maybe you could do it like this

create ciudades model with scaffold

rails g scaffold ciudades nombre_id:integer nombre:integer departamento:string

create municipios model that reference ciudades

rails g scaffold municipios ciudades:references

this will create attribute ciudades_id on the municipios table. The migration should look like this.

class CreateMunicipios < ActiveRecord::Migration
  def self.up
    create_table :municipios do |t|
      t.references :ciudades

      t.timestamps
    end
  end

  def self.down
    drop_table :municipios
  end
end

also on the municipios model it will create the belongs_to relation.

but this does not update the cuidades model. You have to specify the relation.

Also keep in mind that rails automatically create id field on a model. it is the convention. if you mean that nombre_id is the primary key, you have to specify it your self.

Hope this help

Upvotes: 5

user862824
user862824

Reputation:

Scaffold will not create the relationships for you. It will create views, controllers and others but the rest (relationships) need to be coded by hand.

So you scaffold "municipios", but if you want municipio has many ciudades, you need to do it yourself. For example:

When scaffold gives you:

<% form_for([@municipio]) do |f| %>

You need to change it to:

<% form_for([@municipio, @ciudad]) do |f| %>

Upvotes: 0

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